Oral Sessions

S18 SMTA

Oct. 24, 2024 16:00 PM - 18:00 PM

Room: 504B, TaiNEX 1
Session chair: Jeffrey Lee, Integrated Service Technology Inc.

Innovative Interconnect Material for Advanced Packaging Assembly Process
發表編號:S18-3時間:17:00 - 17:30

Invited Speaker

Lim Sze Pei,Senior Global Product Manager,Indium Corp.

As advanced packaging continues to drive towards heterogeneous integration, new materials need to be developed to address the many challenges faced in the assembly process. This presentation will focus on innovative materials for advanced packaging, particularly for small form factor modules, including novel flux formulations for flip chip attach that are compatible with underfill and molding compound, an adhesive agent for fluxless soldering with a formic acid atmosphere, solder paste for ultra-fine pitch printing, solders with various temperatures for hierarchical soldering,
The technology drives toward increased functionality, better efficiency, and higher power density; advanced packaging silicon chip/die size is now bigger, with densely packed interconnect, tighter pitch, and smaller bumps. Some of the common issues we observed due to these are warpage-induced open joints from the big and thin die, flux residue removal challenges due to the tight spacings, and thermal- induced reliability issues. Novel flux formulations and adhesive agents for wafer/die bonding are needed, and interactions between the flux material and various dielectric materials on the wafer need to be better studied. The shift towards using semiconductor-grade ultra-low residue no-clean flip-chip fluxes, which eliminates the cleaning process, is one of the solutions for overcoming these challenges. Another possible solution, studied in recent years, is using a near-zero residue fluxless adhesive agent to hold the die in place while reflowing in a formic acid reflow atmosphere.
The trend of miniaturization and packing more functions in SIP and heterogeneous integration applications makes the assembly process more challenging. With more die and smaller components packed into a tighter footprint, solder paste deposition for high-density applications with ultra-fine pitch requires specially designed solder paste for good and consistent production yield. For fine feature solder paste applications down to 100um or less, fine solder alloy powder quality, flux formulations, and solder paste rheology are crucial to achieving consistent solder paste deposition and good soldering performance.
The development of new solders is also a critical enabler for heterogeneous integration. If there are different reflow cycles that require a solder hierarchy, alloys with varying melting temperatures may be needed for SIP. In addition, lower melting-temperature solders can provide better warpage control, especially for thin die and substrate, as well as for heat-sensitive sensors, die, or substrate that require low-temperature processing. Alloys with enhanced reliability are also needed for certain SIP modules.
In summary, proper selection and application of interconnect materials for various assembly processes is crucial to ensuring high production yield for the assembly process of advanced packaging and SIP application.


 


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